About
character in java.
There is two type:
- char which is a primitive type
- Character which is a primitive wrapper around a char primitive and adds functionalities such as the possibility to store a null value.
They are only manipulated in unicode because the Java platform stores character values using Unicode conventions.
Management
The Character class wraps a char variable but also provides several management methods such as:
- determining a character's category (lowercase letter, digit, etc.)
- or converting characters from uppercase to lowercase and vice versa.
Character information is based on the Unicode Standard, version 6.0.0 and is based on the data file.
Syntax
Init
Literal
Literal value
- A char is quoted in single quote
char c = '"';
Hexadecimal (Unicode)
literal notation where the unicode code point (heaxdecimal) starts with a \u. Example with the box drawing character U+2514
char c = '\u2514';
- From string cldr/utility/character.jsp
((char) Integer.parseInt("2514", 16))
Integer (Unicode)
Java uses an int internaly (and not a hexadecimal) to store an unicode character, therefore you can cast the integer represention of the unicode hexadecimal representation to get a character.
Example with the box drawing character U+2514
- 2514 is equivalent to the number 9492, proof:
int boxDrawAsInt = Integer.parseInt("2514", 16);
System.out.println("Decimal Number: "+boxDrawAsInt);
Decimal Number: 9492
- You can cast it directly
char boxDrawAsChar = (char) 9492;
System.out.println("Box Draw: "+boxDrawAsChar);
Box Draw: └
To
To String
To string …
String.valueOf((char) Integer.parseInt("2514", 16))
To Int
- for a char
int i = (int) '"';
- it works also from a character
int i = (int) ((Character) '"')
To Unicode code point
char c = '⡎';
System.out.println(Integer.toHexString((int) c));
which leads to the character cldr/utility/character.jsp - braille pattern dot
284e
Equality
char c = '\u0000';
char d = 0;
if (c == d){
System.out.println("They are the same");
}
Minus / Addition
Because internally a character is an integer, you can do all integer mathematics operations.
range = (char) this.max - (char) this.min
Repeat
- General
n = 10;
c = 'a'
nc = new String(new char[n]).replace("\0", c);
- From java 11 as the repeat function
"a".repeat(3);
Numeric Value
getNumericValue does not return the int decimal representation of Unicode but the real numeric value of the character following this rule:
- 0 to 9 for the digits
- then the characters below have a numeric values from 10 through 35.
- The letters A-Z in their uppercase ('\u0041' through '\u005A'),
- lowercase ('\u0061' through '\u007A'),
- and full width variant ('\uFF21' through '\uFF3A' and '\uFF41' through '\uFF5A')
Snippet:
if (Character.isDigit(x)) {
int y = Character.getNumericValue(x);
System.out.println(y);
}
Array
Contains
char[] endOfLineCharacters = {(char) 10, (char) 13};
String.valueOf(endOfLineCharacters).contains(String.valueOf((char) 10)));
boolean contains(char[] charArray, char c){
boolean contains = false;
for (char cA : charArray) {
if (cA == c) {
contains = true;
break;
}
}
return contains;
}